Picture-telegraph system



Jan. 28, 1930. A. KORN 1,745,018

PICTURE TELEGRAPH SYSTEM Filed July 28, 1927 Fig'. FLOW Patented Jan.28, 1930 UNITED STATES PATENT OFFICE ARTHUR KORN, OFBERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOR T C. LORENZ AKTIENGESELLSCHAFT,OF BERLIN-TEMPELHOF, 'GERMANY PICTURE-TELEGBAPH SYSTEM Application llledJuly 28, 1927, Serial No.

This invention relates to systems for the synchronization of picturetelegraphs, telautographs and the like.

The synchronization of such devices when only one line of frequenc wasavailable for the transmission was hit erto generally effected in such amanner that synchronizing signals were sent from the transmitting to thereceiving station through the same transmission line or wirelesstransmitting channel during the intervals in which'transmssion ofpicture or writing elements was not taking place.

When rolls or drums were used for the reception of the picture or of thewriting characters at the transmitter or at the receiver, thesynchronization could be effected only after onerevolution, sincebetween the beginning and the end of the lines of the picture or of themanuscript foil there was an interval which could be utilized for thetransmission of the synchronization signals.

In the system of synchronization according to the present inventionthere are transmitted from the transmitting to the receiving stations,simultaneously with the signals to be transmitted, corresponding to thepicture or writing 'character elements, periodic signals of a givenfrequency which are of a different intensity from those of thesuperimposed picture signs, which periodic signals are separated fromthe picture signs at the receiving station and utilized for regulatingthe synchronization.

As current limiting devices for the reception of the synchronizingcurrents there may be used amplifier Valves or other suitable relayswhich exhibit saturation phenomena.

In lorder that the said invention may be clearly understood and readilycarried into' effect, the same will now be described more fully withreference to the accompanying drawings, which illustrate by way of eX`208,936, and in Germany August 3, 1926.

ample two systems of carrying out the invention and in which Figures 1and 2 illustrate respectively in diagrammatic fashion a transmittingstation and a receiving station for wireless transmission.

Figures 3, 4 and 5 are various diagrams of the frequencies utilized for.the purpose in view,

Figure 6 shows a transmitting station for line transmission, and

Figures 7 8 and 9 are various diagrams of the frequencies generated inthe case of the arrangement shown in Figure 6.

Fig. l() is a diagrammatic view of the receiver.

.In Figure 1 there is shown a well known telautographic transmitter inwhich a rotatable metal cylinder 1 carries a metalfoil on which thepicture to be transmitted is traced in a non-conducting substance.

A metal feeler pin 2 makes or does not make contact on the foilaccording as it strikes a conducting or a nonconducting point of thepicture. -With the cylinder 1' there rotates an interrupter disc 4 onwhich a n spring 4f periodically makes contact. The voltages from abattery 3 pass through the resista-nce 5, the interrupter disc 4 andthrough the resistance 6, which is connected in parallel to thetelautographic transmitter, into the grid of a wireless transmitter orinto a modulation valve of -such a transmitter; the path to the latteris indicated by the plug contact 7.

As longas the feeler pin 2 does not make contact periodic synchronizingsignals of the kind shown in Figure 5 will be produced. As soon howeveras the feeler pin 2 makes contact, the signals corresponding to thepicture 35 elements are superimposed, since the resist ance 6 is now cutout, on top of the synchronizing current impulses` determinedby theinterrupter disc 4 and its speed of rotation, for instance in the mannerindicated in Fig- 90 In e reivin a paratus shown in Figure 2, the signsw ic are received by means 15 (supplied from the an of the highfrequency or intermediate frequency amplification and audion (detector)and which are again of the shape shown in `Figure 3, are passed throughthe plug oontact 8 into a thermionic valve 9 in such manner that thevoltages, which are of the shape according to Figure 3, are conveyedbetween the grid 9 and the cathode 10, and, proportionally amplified,chan e the anode current e battery 12) which asses from the cathode tothe anode 11. e anode current passes through the photographic picturereceiver 13 (lstringgalvanometer, oscillograph or the ike; voltage regoceivers such as glow light tubes and Kerr cells could also be suitablycontrolled by the changes eHected by the thermionic valve 9), in whichthev resence of the synchronizing current impu need not be considered z5so far as re ards the reception of the picture. For o taining thislatter purpose, the string galvanometer could be set for instance insuch a manner that for the frequency signs it is deflected merely to anextent at which so a production of icture docs not take place.

Only signals, the intensity of which is greater than that of the f uencysigns, produce an effective deflection o the galvanometer. Obviously,however, the reverse might be the case, i. e., the synchronizing signsmay be of greater intensity than the picture signs and the galvanometermay be so adj usted that it will not be deflected by the synchronizingsigns alone but only when the current is of a certain amplitude, thatis, when the picture signs are present with the synchronizing slilisorder to utilize the frequency signs for the regulation of asynchronous motor-the path to the same is indicated by 18-separatelyfrom the picture signs, the anode current of the valve 9 is amplifiedonce more b sending the current from the positive end of' the battery 12through a resistance 14 and by applying the potential behind the saidresistance to the grid 15 of the valve l5; the cathode 16 receives itspotential from a suitable intermediate point of the battery 12; a stillfurther amplified anode current from the cathode 16 to the anode 17 isobtained from the anode battery 19. This amplified current, which is tobe used for the regulation of the synchronous motor in the receivershould already have such an intensity that in the case of the frequencysigns saturation isreached, whilst the picture signs in the same shouldno longer be noticeable. {[n place of the telautographic transmitterthere could also be used a transmitter operated by the photoelectriccell system, in which the influence.

picture signs are not merely es and no signs, but signs which are gra edto suit the picture elements and which are superimposed on the fr uencysigns, so that the si assume the s a shown in Figure 4. e arrangementsin the receiving apgiaratus remain the same. In the case o black andwhite pictures, even when photo-electric cells are used thesignsreaching the receiver will again have the shape shown in Figure 8.

When it is a uestion of transmission through wires, an when thearrangement with the interrupterv disc 4 is used in the transmitter, itwill no longer ,be so' easy to separate the frequency signs from thepicture signs in the receiver on account of the flattenin of the signsby the capacity or this purpose there is then used the arrangementaccording to Figure 6.

In this last mentioned arrangement 20 is an alternating currentgenerator, the frequency of which is determined by the capacity of theline. The alternating currents go through the inductance 21, arranged inparallel to t e telautographic transmitter 1, 2, through the plugcontact 7 into the line. As long as the feeler pin 2 does not makecontact, periodic signs of the form shown in Figure 7 will be produced.As soon however as the pin 2 makes contact, the signs corres riding tothe picture will be superimpose since the inductance 21 is then cut out,on the frefuency signs, for instance in the manner inicated in Figure 8JThe arrangement in the receiving apparatus remains as shown in Figure 2,only the signs coming through the plu contact 8 will not come from theaudion detector) of a wireless transmitter, but direct from the line. Inplaceof the telautogra hic transmitter, there can also be used in t iscase a transmitter worked by the photo-electric cell system; the signscoming from the transmitter could then instead of being of the sha shownin Figure 8, also be for instance of t e shape shown in Figure 9. Thereceiver arrangement in this latter case would again remain the same.

What I claim to be secured by Letters Patent is:

1. In a picture transmitting system, a first station, a second station,means at the first station for generating synchronizin impulses ofamplitudes having up r an lower predetermined limits, means gdrgeneratin picture impulses of varying amplitudes aving upper and lowerpredetermined limits, said amplitude limits of said picture transmittingimpulses being outside of the range of said synchronizing impulses andmeans at the second station for separating said icture and saidsynchronizing impulses.

2. n a picture transmitting system` a first station, a second station,means at the first station for generating synchronizing currents lll ofamplitudes having upper and lower'predetermined limits, means forgenerating picture currents of varying amplitudes having upper and lowerpredetermined limits said amplitu-le limits of said picture transmittingcurrents being outside of the range of said synchronizing currents andamplitude responsive means at the second station for separating saidpicture and said synchronizmg currents. i c

3. In a signalling system, a first station, a second station, means forgenerating synchronizing impulses at said first station having upper andlower amplitude limits of a predetermined value, means for generatingsignalling impulses, having upper and lower amplitude limits, saidamplitude limits of said signalling impulses being outside the range oflimits of said synchronizing impulses and means at the second stationfor separating said signalling and said synchronizing impulses.

4. In a signalling system, a first station, a second station, signallingapparatus at said stations, means for generating synchronizing impulsesat said rst station, having upper and lower amplitude limits ofpredetermined value, means for generating signalling current havingupper and lower limits of predetermined value, the lowest amplitudelimit of said signalling current being as great as the highest amplitudelimit of the synchronizing currents, means whereby said synchronizingcurrents maintain the signallin apparatus in synchronism, means where ysaid signalling apparatus operate in response to said signallingcurrents and amplitude distinguishing means at said second station forseparating said signalling and sychronizing impulses.

5. In combination with an electric signalling system havingsynchronously operating transmittin and receiving elements, means fortransmitting simultaneously signalling currents and synchronizingcurrent impulses on a common transmission channel, comprising means toproduce periodic sychronizing current impulses, further-means associatedtherewith to produce signalling current signals having a zero levelequal to the top level of said synchronizing currents, a receivingdevice for said signalling currents adapted to become operative onlywith a biasing current at least equal to the strength ofsaidsynchronizing currents, and a current limiting device to serve as asegregating means for said synchronizing currents having its limitingvalue adjusted to be equal .to the strength of said synchronizingcurrents.

6. In combination with an electric signalling system havingsynchronously operating transmitting and receiving elements, means forsimultaneously transmitting signalling currents and synchronizingcurrent impulses over a common circuit comprising means to produceperiodic synchronizing current impulses, further means associated withsaid first means to produce signalling current signals having a zerolevel equal'to the top level of said s nchronizing currents, agalvanometer receiving device for said signalling currents so adjustedas to register receiving currents of reater than maximum intensity ofsaid sync ronizing impulsesonl and a discharge device having cathode ananode electrodes to produce discharge currents therebetween, controlmeans or said discharge current, a common receiving circuitincludingsaid galvanometer device and coupled with said control means, saidcontrol means being adjusted so as to effect saturation of saiddischarge current with a current fiowing in said receiving circuit notgreater than the maximum strength of said synchronizing currents.

7. In combination with an electric picture transmission system, havingsynchronously operating transmitting and receiving ele'- ments, meansfor transmitting simultaneously synchronizing current impulses andpicturecurrent signals on a common transmission channel comprising meansto produce periodic synchronizing current impulses, further meansassociatedy with said first means to produce picture current signals inaccordance With the scanning elements of a picture to be transmitted andhaving a zero level above the top level of said synchronizing currents,a receiving device for said picture current adapted to become operativewith a biasing current at least equal to the strength of saidsynchronizing currents, and a current limiting device to serve as asegregating means for'said synchronizing currents having its limitingcurrent adjusted to be equal to the strength of said synchronizingcurrents.

8. In combination with an electric picture transmission system,. havingsynchronously operating transmitting and receiving elements, means fortransmitting simultaneously synchronizing current impulses and picturecurrent signals on a common transmission channel, comprising means toproduce periodic synchronizing current impulses, further meansassociated withA said first means to produce picture current signals inaccordance with the scanning elements of a picture to be transmitted andhaving a zero level equal to the top level of said synchronizingcurrents, a galvanometer picture-receiving device adjusted so as toregister currents of greater than maximum intensity of saidsynchronizing currents, and a discharge device having cathode and anodeelectrodes to produce the discharge current thereby, control means orsaid discharge current, a common receiving circuit including saidgalvanometer device and coupled to said control -pulses with the means,said' control means being adjusted te y eect saturation of saiddischarge current with a current flowing in said receiving circuit equalto the strength of said synchronizing currents.

9. In combination with an electric picture' transmission system havingsynchronously operating transmitting an receiving elements, means forproducing, transmitting simultaneously on a common channel, and segreting from each other picture current signal: and synchronizing currentim ulses, comprising a transmitting circuit inc uding in series acurrent source and a picture scandevice, means to interrupt said circuitperiodically during short intervals synchronously with the speed of saidscanning device to roduce synchronizing current imicture signals placedon the top level thereog a common receiving circuit for both saidsynchronizing currents and picture currents, a light valve in saidreceiving circuit having its shutter so adjusted as to obstruct thepassage of light on currents smaller than said synchronizing currents,and a three electrode vacuum tube for segregating said synchronizingcurrents having its grid circuit coupled to said receiving circuit andAadjusted in such a manner as to become saturated at a receiving currentnot greater than said synchronizing currents.

10. In combination with an electric picture transmission system, havingsynchronously operating transmitting and receiving elements, means forproducing, transmitting simultaneously on a common channel andsegregating from each other picture current signa s and synchronizingcurrent impulses, comprising a transmitting circuit inc uding in aseries a current source, a picture scannin device, a circuitinterrupting device operate synchronously with the scanning of saidscanning device, whereby ri ic synchronizing current im ulses Wit smallspacing intervals are ro uced having the picture current signa placed onthe top level thereof, a common receiving circuit for said picturecurrents and synchronizing currents ia li ht valve in said receivingcircuit arran an adjusted as to obstruct the passage of light forcurrents smaller than the top level intensity of said synchronizingimpulses, a three electrode vacuum tube for segregating saidsynchronizing currents having main elecode and a control electrode, abiasing battefy in series with a coupling resistance connected to saidcontrol electrode and also coupled with said receiving circuit and soadjusted as to elect saturation of the output current of said vacuumtube with current in said receiving circuit not greater than saidsynchronizin currents.

11. In com ination with a icture transmission system, means forsimultaneously transmitting synchronizing current impulses and picturesignal currents, comprising means for producing periodic chronizingcurrent impulses having smal spacing intervals, further means associatedwith laid first means to produce picture current nals having as a 1eroamplitude level tep amplitude level of said sync impulses and means forse ting both currents consisting respective of a device acqui i a biasat least equa to the tep value of sai synchroniz' currents and a currentlimiting device ha a limit value not greater than the intensity of saidsynchronizilxg impulses.

In a picture ton system using synchronously operating transmitting andrec eiving elements, the method of transmi simultaneously on a commonchannel an separating from each other, sync current impulses and icturesignal currents which consists in placing the icture signale on adifferent amplitude leve equal thereon the synchronizing currentimpulses and separating both currents, by the synchronizing currents asoperating bi current and as limiti current for the picture currentreceiver ail the synchronizing current receiver respectively.

13. In a picture traon system synchronously operating transmitting andreceiving elements the method of transmittin simultaneously on a commonchannel an separating from-each other, synchronizing current impulsesand icture signal currents which consists in placin the icture signalson a different amplitu e leve ual thereon the synchronizing current impand se arating both currents.

14. 'picture tion system having synchronously operating scanning devicesand picture reproducing apparatus, means to transmit unilateral picturecurrent impulses varying in accordance with picture characteristics ofelementary portions of the picture to be transmitted, further means fortransmitting unilateral riodic synchronizing current impulses caracteristic of the scanniii speed of said picture, both series of impuses being superimposed upon each other for transmission over a commonelectric channelz and means at the receiving end for separating saidimpulses from each other, said last means comprising marginal currentresponsive devices adjusted in respect to the intensit values of saidpicture current impulses an said synchronizing current impulsesrespectively.

15. In a picture transmission system having a picture transmittingstation and a picture receiving station remotel disposed from eachother, an image at said transmitting station, means for translatingelementary portions of said image into variable direct currents inaccordance with variations of lll `the image characteristics, furthermeans l simultaneously operative with said translat- 'ing means fortransmitting direct current periodic synchronizing currents inaccordance with the speed of operation of the translating means incovering successive portions of the picture, the picture andsynchronizing currents being superimposed .upon each other and upon acommon electric channel and current responsive means at the receivingsiation for separating said picture and synchronizing currents from eachother.

In testimony whereof I have aixed my signature.

ARTHUR KORN.

